Blast furnace charging apparatus and method



July 30, 1968 w. E. SLAGLEY ETAL Filed Oct. 17, 1966 3 ,394,82 6 BLAST FURNACE CHARGING APPARATUS AND METHOD 4 Sheets-Sheet 1 :37 50 Jam/area INVFI/ To:

Mieeg )7 nrropa/srs y 0, 1968 w. E. SLAGLEY ETAL 3,394,826

BLAST FURNACE CHARGING APPARATUS AND METHOD Filed Oct. 17, 1966 4 Sheets-Sheet 2 prraeA/lns July 30, 1968 w. E. SLAGLEY ETAL 3,394,826

BLAST FURNACE CHARGING APPARATUS AND METHOD 4 Sheets-Sheet 5 Filed Oct. 17, 1966 AVVA'A/TQPS y 0, 1968 w. E. SLAGLEY ETAL 3,394,826

BLAST FURNACE CHARGING APPARATUS AND METHOD 4 Sheets-Sheet 4 Filed Oct. 17, 1966 United States Patent 3,394,826 BLAST FURNACE CHARGING APPARATUS AND METHOD William E. Slagley, Crown Point, and Lawrence G. Maloney, Munster, Ind., assignorsto Inland Steel Company, Chicago, 111., a corporation of Delaware Filed Oct. 17, 1966, Ser. No. 587,282

r 21 Claims. (Cl. 214-35) This invention relates to process vessels which operate at an internal pressure different than the exterior pressure and methods of supplying material to the inside of the vessel without significantly altering the vessel internal pressure.

Many industrial operations are conducted in vessels which operate at internal pressures different than external pressures. The internal pressure of the vessel can be higher or lower than the external pressure, which often is atmospheric pressure. It is often required in a process being effected in the vessel that various materials be supplied thereto from outside without significantly varying the vessel internal pressure, which it is essential be maintained in many instances during operation of the process. Various processes require, in addition to maintenance of the vessel internal pressure, that the operation be effected at relatively high temperatures. Thus, Whatever charging apparatus is required to supply the material to the vessel interior must be capable of maintaining the differential pressure and also be relatively unaffected by operation at relatively high temperatures.

The blast furnace is a specific illustration of a vessel which is operated at an internal pressure differential compared to the external pressure, and which also involves high temperatures of operation. Changing of the necessary ingredients for producing iron in a blast furnace requires apparatus which will permit the furnace to operate at an internal pressure at least about one to three lbs. per sq. in. higher than the external pressure. Such pressures, however, are relatively low and for efficient blast furnace operation and increased production of iron, the industry has been emphasizing operating blast furnaces at substantially higher top pressures, such as around ten lbs. per sq. in. gauge, and more suitably in the neighborhood of about 25 lbs. per sq. in. gauge and higher. Charging apparatus which can function satisfactorily and maintain low differential pressures of about one to three lbs. per sq. in. gauge does not perform satisfactorily for a sufficient length of time at the higher top pressures.

The conventional apparatus for charging a blast furnace operating at a high top pressure involves a series of two to three conventional bells and associated hoppers. See Slagley US. Patent 3,152,703. The bells are generally of cast alloy iron or steel and are expensive to produce and replace.

One of the difficulties with the conventional bell and hopper system for supplying material, generally called burden, to a blast furnace for producing iron has been the inability to suitably maintain an adequate pressure seal between the bell seat and the hopper. A seal need not be completely tight at the low pressures of about one to three lbs. per sq. in. gauge, but when the pressure is increased to about ten or more lbs. per sq. in. gauge, the absence of a tight seal lets hot gases and highly abrasive dust particles blow by the seal and erode the apparatus to the point Where channels are created rendering it impossible later to obtain any kind of a satisfactory The bells and hoppers also warp and this further defeats obtaining-the required sealing. Thus, a bell seat which can operate succesfully for a full campaign of from five to seven years at one to three lbs. per sq. in. gauge pressure is reduced to a useful life of about two years at about ten lbs. per sq. in. gauge pressure, and at pressures of about 3,394,826 Patented July 30, 1968 25 lbs. per sq. in. gauge a short life of about six to nine months can be expected.

When it is necessary to replace or repair the bell and hopper charging unit, a shut-down time of up to five days or more may be required. This delay, plus replacement of the worn-out equipment, entails a large, economic loss. A charging system which will run at high top pressures for a long time without replacement, and which can be replaced in a few hours when necessary would serve to reduce costs and increase production.

Slagley US Patent 3,152,703, of which one of us is the patentee, discloses a two-bell and hopper system for charging burden to a blast furnace. The apparatus shown there is conventional except that expandable sealing means are provided for achieving the seal between the bell and the hopper. Such sealing means will function satisfactorily and overcome many of the drawbacks associated with conventional bell and hopper systems used for charging burden to a blast furnace. However, even that bell and hopper system requires an unnecessarily large capital investment and this, of course, makes replacement and repair costly. Also, it, as well as conventional bell and hopper systems, requires that the burden be hand-led three to four times as it fiows to the furnace. Each time it moves it ab-rades the hopper and bell surfaces, and lowers the equipment life. In addition, the gas pressure in the volumes or spaces to be equalized when transferring the burden from one bell and hopper to the next, and then into the furnace, to avoid blowing gases and dust out the furnace top, requires pressurizing and depressurizing unduly large volumes.

There is provided according to the subject invention, novel apparatus for delivering material to a vessel, particularly a blast furnace, having an internal gas pressure different than the external gas pressure applied to the vessel, comprising: an opening in the vessel through which material can be delivered or supplied from outside to inside the vessel; closure means which movably plugs and closes the vessel opening to keep the vessel internal gas pressure different than the external pressure; a material-receiving, open-mouthed, hollow receptacle movably mounted in the vessel so that the mouth can be brought into communication with the vessel opening; sealing means for blocking passage of gas between the vessel interior and exterior, at least when the vessel opening is opened, said sealing means circumscribing the vessel opening and receptacle mouth and being capable of spanning the distance between the receptacle outer surface and vessel inner surface; and receptacle moving means to displace the receptacle so that material therein can flow from the receptacle through its mouth and into the vessel. The sealing means advisably comprises a seal extendible by fluid pressure into sealing engagement between the receptacle outer surface and vessel inner surface. In addition, the apparatus advisably includes a seal extendible by fluid pressure for securely sealing the closure means in the vessel opening. Other features of the invention will be described subsequently and it should be understood such additional features in themselves are considered of an inventive nature even though not specifically referred to above.

The invention will be described hereinafter with specific reference to utilization of the invention in a blast furnace, and as shown in the drawings:

FIG. 1 is a vertical sectional view of the top portion of a blast furnace having the novel burden charging apparatus of this invention;

FIG. 2 is an enlarged view showing an expandible sealing means for sealing the distance between the inside of the blast furnace wall and the outside of the receptacle around the receptacle mouth opening;

FIG. 3 is similar to FIG. 1 but in lesser detail, and

3 shows the closure means in removed position with the furnace opening fully open;

FIG. 4 is a vertical section showing part of the furnace top and part of the receptacle and another embodiment of an expandible seal for sealing the space therebetween;

FIG. 5 is a sectional view taken along the line 55 of FIG. 4;

FIG. 6 shows another receptacle shape in which the bottom is spherical and the top is a conical section;

FIG. 7 also shows another receptacle shape in which the bottom is elliptical and the upper part is a conical section; I,

FIG. 8 shows still another shape of the receptacle in which both the lower and upper parts are more or less elliptical in shape; FIG. 9 is an enlarged elevational view of the gratelike skirt portion suspended inside the furnace; and v FIG. 10 is a side view of the grate-like skirt-portion of FIG. 9, showing how it retains burden. against passage therethrough.

In the drawings and the following discussion, thesame numbers will be usedfor the same or similar elements so far as is consistent with clarity.

With reference to FIG. 1, there is shown the upper portion of a blast furnace 10. At the top of the furnace, top cone 11 covers much of the area and at its upper edge, there is provided top ring 12 which supports cover section 13. Pipes 14 provide for removal of gases produced during the production of iron in the blast furnace. Cover section 13 has bearing supports 15 which support the shafts 16 extending from opposite sides of the material-receiving hollow receptacle 17 shown as a spherical-shaped shell. Motor 18 drives gear reduction units 19 for moving receptacle 17 about its horizontal axis on shafts 16. Receptacle 17 can be caused to rotate only partially, such as back and forth through a 180 arc from an upright to an inverted position, or it can be arranged to rotate completely around through a 360 arc. As the receptacle 17 rotates, material or burden 20 therein flows by gravity and is deposited at the top of the burden column 21 inside the furnace. Mouth 92 is provided in receptacle 17 for receiving burden therein and discharging the same as it is rotated. Mounted on the top edge of cover section 13 is element 22 having an upper ring-like structure which circumscribes an opening in the top of the blast furnace. A collar 23 can, if desired, be inserted inside the opening 27 in order to provide a wear surface.

Expandable seal 24 positioned in steel element 22 is actuated by fluid under pressure supplied by means of conduit 25. The fluid is removed from the expandable seal 24 by means of conduit 26, there being suflicient resistance to flow of the fluid to expand the seal and bring it into sealing engagement with the outer surface of the spherical receptacle 17. The fluid used to actuate seal 24 can be either a liquid, such as water or oil, or a gas, such as air. It is desirable that the fluid be circulated through the corridor 24a in back of seal 24 in order to cool the seal and prevent over-heating it. However, circulating the liquid is not essential if the seal is made out of material which can withstand the temperatures involved at the furnace top throughout continuous operation. US. Patent 3,152,703 gives additional information on the described seal and means for cooling the fluid to remove heat absorbed in the seal and such disclosure is incorporated herein by reference.

As shown in FIG. 1, seal 24 can be made of an elastomer material which is heat-resistant and impervious at normal operating temperatures to gases and liquids it contacts. Elastomers, such as vinylidene fluoride-hexafluoropropylene type copolymers are useable, such as described in Industrial and Engineering Chemistry, vol. 49, p. 1687, October, 1957. Particularly suitable elastomers are sold under the names Viton A-HV and Viton A. The elastomer seal can be a strip-like, flexible, resiliently deformable member having one large surface disposed toward the receptacle and another large surface area disposed toward the inside wall surface of the furnace, thus forming corridor 24a as shown in FIG. 2. Seal 24 is positioned to circumscribe the receptacle mouth 92 and also circumscribe the opening 27 in the furnace top. Furthermore, seal 24 is advisably positioned on the inside surface of the furnace so that it is out of the path of burden poured into receptacle 17. The seal thus contacts the outside of the receptacle while the burden wears on the inside. All prior systems tried to seal against the same surface that the burden is wearing against.

Mounted at the top of furnace opening 27 is hopper 28 having a lower section 29 and an upper portion 30. Sections 29 and 30. are elliptical in horizontal crosssection, making them extra wide to accommodate two skips, side-by-side. Arm 32 retracts in the space between the two skips. Section 30 of the hopper has a cut-away portion 31 in order for the pivotally mounted arm 32 supporting the closure means 33 to be moved completely in and out of the hopper 28 for opening and closing furnace opening 27. Thus, the actuating arm 32 is pivoted at 32a and is caused to moved by tension applied to cable 34. Weights 35 cause the closure plug or stopper 33 to rotate down into position to seal the furnace opening 27 when tension released on cable 34.

Mounted about the lower periphery of closure 33 is expandable seal 36. As shown in FIG. 1, the seal 36 is comprised of an elastomer strip which goes completely around closure plug 33. Seal 36 is expanded by means of fluid fed by pipe 37 which communicates with pipe 38 to supply fluid into seal corridor 36a as shown more clearly in FIG. 2. If fluid circulation is desirable, twE) pipes could be used, one supply and one return.

Pipe 39 feeds gas under pressure, in those furnaces where this is necessary or advisable, to the upper part of the furnace, namely that space between seal 36 on the closure plug 33 and seal 24 which contacts the receptacle 17. As a result, that space, including the space inside of receptacle 17, can be brought up to any suitable pressure. In operation of a high-top-pressure furnace, the pressure can be brought up to about equal or above the pressure inside the furnace.

Pipe 40 serves as a means to remove gas from the upper part of the furnace to equalize the pressure therein at such time as this is desirable, such as after seal 24 is actuated into contact with the receptacle 17 and before seal 36 is released and closure plug 33 removed.

FIG. 2 illustrates in greater detail the seals 24 and 36 used respectively to seal the receptacle 17 to the furnace, and the closure plug 33 to the furnace opening 27. The elastomer strip of seal 24 is held in place by metal strips 41, secured by suitable means such as bolts. Similar metal strips 42 are used to hold the elastomer seal strip 36 in position. Also as shown in FIGURE 2, mouth 92 of receptacle 17 is larger than the opening 27 in the furnace so when the opening and the mouth are in substantial alignment, the burdens of coke, iron ore pellets, sinter and limstone fed to the furnace fall from hopper 28 directly into receptacle 17 and do not spill over the outside of the receptacle. I Seal 24 is shown .more clearly in FIG. 2 mounted on the inside surface of the furnace. This position is preferred overmounting the seal on the receptacle since its location as shown renders it less likely to be hit by falling burden. This is furthermore why seal 36 is advisably positioned around the periphery of the closure plug 33 rather than in the opening 27. Both seal 24 and seal 36 are illustrated in FIG. 2 in-a relaxed or pressure-released position.

In operating the burden charging apparatus provided by this invention with the blast furnace in use producing iron, closure plug 33 is positioned in furnace opening 27 and fluid pressure applied by means of conduit 37 to expand elastomer seal 36 into contact with the inner surface wall of opening 27. Receptacle 17 is then moved so mouth 92.is in substantial alignment with furnace opening 27, during which operation the opening is, of course, closed by plug 33-Fluid pressure is then applied by means of conduit 25 to expand elastomer seal 24 into contact with the outer receptacle surface. At this point, receptacle 17 is empty or it may contain a small amount of residual material or burden in the bottom to act as a cushion for the incoming load. The fluid pressure on elastomerseal 36 is released and tension applied to cable 34 to raise closure plug 33 out of the furnace opening 27, as shown more clearly in FIGURE 3. In this specific embodiment, the closure is shown completely out of furnace opening 27 and essentially out of hopper 28. The furnace charge or burden is then conveyed by suitable means, such as a skip car or conveyor belt, to the inside of hopper 28 from which it falls by gravity directly into receptacle 17. After a suitable amount of burden has been deposited in receptacle 17, the closure plug 33 is repositioned in furnace opening 27 and fluid pressure applied to elastomer seal 36 by means of pipe 37. The apparatus is then as shown in FIGURE 1. By means of pipe 39, gas pressure is applied to the inside of the furnace while seal 24 is kept pressurized into contact with receptacle 17. This equalizing of pressure avoids blowing hot gases and abrasive particles upwardly past seal 24 and into the upper part of the charging apparatus. Once the pressure in the upper part of the furnace has been equalized, supplying of gas by conduit 39 is discontinued and the fluid pressure on seal 24 released. Now the sole means retaining the blast furnace pressure is elastomer seal 36 which secures closure plug 33 in furnace opening 27. Receptacle 17 is now free to move and can be rotated until burden 20 pours from its mouth 92 onto burden column 21 immediately therebelow. After emptying receptacle 17, it is rotated until mouth 92 is at the top and in line with furnace opening 27. Seal 24 is then actuated into contact with the receptacle and, by means of pipe 40, gas is removed from the upper part of the furnace to equalize the pressure therein to the pressure outside of the furnace. By reducing the pressure in this manner, the gas in the upper part of the furnace, and particularly inside receptacle 17, does not expand and cause the blowing of abrasive dust particles and hot gases upwardly through opening 27 when plug 33 is removed. Once the pressure has been suitably reduced, seal 36 around the circumference of the closure stopper plug 33 is released permitting removal of the plug and its movement into position as shown In FIG. 3. Then, an additional burden charge can be conveyed into hopper 28 and the procedure repeated. In charging the furnace in this manner, the burden comes in contact only with the inside of hopper 28 before. it falls directly into receptacle 17. Receptacle 17 can be cast of a wear-resistant metal and be of suflicient size to hold any suitable amount of burden, such as one skip car load of burden. The mouth 92 can have an opening of approximately 4 ft. in diameter.

With reference to FIG. 1, the closure plug 33 can be so constructed that in addition to having seal 36 used to prevent passage of gas, the upper surface 45 can be so formed as to have an outer surface which permits nesting of the closure plug in the lower portion of the conical section 29 of the hopper, thus providing a metal-to-metal seal in addition to the seal 36.

FIGS. 4 and 5 show an alternative structure which can be used to seal the space between the furnace and the receptable. The upper part of the furnace is provided with a seal ring 50, into which a plurality of expansion cylinders 51 are placed in spaced-apart position as shown clearly in FIG. 5. Floating seal 52 is caused to move up and down by expansion cylinders 51 which are actuated by fluid under pressure supplied by pipeline 53. Expansion joint curtain 54 of gas impermeable material prevents passage of gas between the furnace wall and the receptacle when the seat 52 has been actuated into contact with the receptacle.

Although the receptacle 17 for receiving bur-den or solid fiowable material is shown in FIGS. 1 to 3 as spherical, the receptacle may have other shapes. As shown in FIGURE 6, the receptacle may have a lower spherical shell portion 60 and an upper conical shell section 61. Also, as shown in FIG. 7, the receptacle can have a lower elliptical shell portion 62 and an upper conical shell section 63. Still another shape is shown in FIG. 8 where the receptacle has a lower elliptical shell portion 64 and an upper elliptical shell portion 65. Each of the receptacles shown in FIGS. 6 to 8 is shown for illustrative purposes located with its mouth 92 upright and about two-thirds full of burden 20.

An important additional feature of this invention is the provision of a downwardly depending skirt suspended from inside the furnace top. The skirt 80 is advisably cylindrical in section and has a diameter substantially larger than the receptacle mouth 92, and advisably also larger than the diameter of the receptacle, so that burden emptied from the receptacle will fall between the skirt periphery. Although the skirt can be a unitary structure, it is advisable for optimum performance that it have an upper insulated portion and a lower portion suspended therefrom of grate or grid-like structure. Thus, metal shell 81 can be suspended from the inside of the furnace top and its exterior insulated 82. The insulation retards heat from penetrating into the upper part of the furnace and raising the temperature of the charging apparatus unduly high. The lower part of the skirt can be composed of a grid-like structure 83, one embodiment of which is more clearly shown in FIGS. 9 and 10. The hanging grate or grid is composed of a plurality of similar inclined plates 84 having spacer elements 85 on the top and spacer elements 86 at the bottom of both ends of the plates. Elements 85 and 86 would desirably be cast integral with plate 84. The spacer elements 85 and 86 are provided with holes which receive vertical rods 87 suspended from the bottom periphery of metal shell 81. Each plate can be secured separately, such as by retaining lugs or bolts, to rods 87 so that if lower plates are destroyed or slip off during furnace operation the remaining plates will be retained in place on rods 87. The plates 84 are all similarly suspended at an inwardly directed downward angle so that the blast furnace burden is retained within the skirt, yet permitting passage of furnace gases through the burden and out the open spaces in the grate. The grate thus functions in the manner of a Venetian blind which permits passage of air but here, instead of blocking light, blocks the burden.

As shown more clearly in FIG. 1, suspended grate 83 retains the burden therein and permits it to flow only out the bottom edge 90. The burden flows from such centrally located reservoir or column 21 to any side of the furnace where consumption of the burden requires the addition of more material. A stock line armour ring 91 can be provided inside the furnace to protect against excessive wear at the top edge of the burden. Thus, the use of stack line wearing plates is eliminated with this charging apparatus since the receptacle and suspended grate structure keeps the burden from falling directly against the furnace wall. The suspended grate or grid structure 83 also exposes more of the top of the burden and increases the surface area through which gas provided in the furnace can exist, thus permitting lower gas velocities and reduced blowing dust. The suspended grate structure also allows close control to the fill mark on the furnace. The burden automatically flows to that side of the furnace which is working faster, keeping a uni form fill level without the necessity of having a burden distributor used for that purpose, especially when ideal beneficiated free-flowing burden is employed. Also, the column of burden 21 confined 'by the hanging grate 83 cools the gas because the gas passes through the burden most recently charged into the furnace and which is therefore the coldest burden. Thus, any gas which reaches the charging mechanism in the top of the furnace is not likely to have an adverse eflect upon seals 24 and 36. Furthermore, the insulated portion of the skirt is readily made sufliciently large so that the burden falling from the receptacle does not strike it but falls directly onto the burden below, thus prolonging the useful life of the insulated portion of the skirt. The burden column 21 also serves as a surge capacity by providing burden to the furnace evenly in spite of intermittent charging of skips or conveyor loads to the furnace.

The burden level in the furnace can be indicated by any suitable means, such as by radioactive devices, radar, light, sound or other conventional means. Also, one can sight horizontally or obliquely straight across the furnace through the spaces between individual grates 84. The described charging apparatus lends itself to ready repair and replacement. The entire upper unit containing the receptacle can be removed from the furnace and replaced with a similar unit. It is contemplated that cast iron element 22 containing seal 24 can be replaced within a matter of a few hours as compared to four or five days needed to replace and repair the charging bells and hoppers used in conventional blast furnaces.

By eliminating the need for two to three charging bells and associated hoppers, the height of the blast furnace can be reduced as much as twenty feet. Thus, the superstructure needed for loading skips and conveyor belts can also be shortened resulting in a substantial reduction in capital investment. Also, the hoisting mechanisms for for the charging bells used in conventional systems is eliminated with substantial savings. Furthermore, when it is necessary to equalize the furnace top using the subject invention, only a volume of about 200 to 500 cu. ft. need be equalized as compared to approximately 1,000 to 2,000 cu. ft. between the bells on conventional furnaces, with even larger volumes involved when three charging bells are employed.

The burden inside the receptacle 17 would roll primarily on itself with only internal abrasion. The wall thickness of the receptacle could be varied according to the wear pattern, as for example, the bottom of the receptacle could be of increased thickness to absorb the burden as poured in.

Various changes and modifications of the invention can be made and, to the extent that such variations incorporate the spirit of this invention, they are intended to be included within the scope of the appended claims.

What is claimed is:

1. Apparatus for delivering material to a vessel having an internal gas pressure diflerent than the external gas pressure applied to the vessel comprising:

a vessel having an opening through which material can be delivered or supplied from outside to inside the vessel;

closure means which movably plugs and closes the vessel opening to keep the vessel internal gas pressure different than the external pressure;

a material-receiving open-mouthed hollow receptacle movably mounted in the vessel so that the mouth can be brought into communication with the vessel opening;

sealing means for blocking passage of gas between the vessel interior and exterior at least when the vessel opening is open, said sealing means circumscribing the vessel opening and receptacle mouth and being capable of spanning the distance between the receptacle outer surface and vessel inner surface; and

receptacle moving means to displace the receptacle and pour material from the receptacle through the mouth and into the vessel.

2. Apparatus according to claim 1 in which the sealing means is extendible by fluid pressure into sealing engagement between the .receptacle outer surface and vessel inner surface.

3. Apparatus according to claim 1 including a sealing means extendible by fluid pressure for securely sealing the closure means in the vessel opening.

4. Apparatus according to claim 1 in which the vessel opening and receptacle mouth are substantially aligned and horizontally positioned, and the receptacle is mounted to rotate about a horizontal axis to empty material therefrom by gravity flow.

5. Apparatus according to claim 2 in which the seal is mounted to the inside wall of the vessel.

6. Apparatus according to claim 3 in which the seal is mounted around the periphery of the closure means and is extendible into contact with a wall surface of the vessel opening.

7. Apparatus according to claim 1 having gas conduit means for delivering gas to the vessel in the space before the closure means and ahead of the sealing means circumscribing the receptacle mouth to thereby increase the gas pressure in such space independent of the gas pressure in the remainder of the vessel interior.

8. Apparatus according to claim 1 having gas conduit means for removing gas from the vessel in the space before the closure means and ahead of the sealing means circumscribing the receptacle mouth to thereby lower the gas pressure in such space independent of the gas pressure in the remainder of the vessel interior.

9. Apparatus for charging burden to a blast furnace operating at a high top pressure comprising:

a blast furnace having an opening at the top through which burden can be supplied to the furnace;

closure means which movably plugs and closes the blast furnace opening to keep the furnace pressure higher than atmospheric. pressure;

a burden-receiving open-mouthed hollow receptacle movably mounted in the vessel so that the mouth can be brought into burden-receiving alignment with the furnace opening;

sealing means circumscribing the furnace opening and receptacle mouth which prevents gas flow between the receptacle outer surface and furnace inner surface at least when the furnace opening is open; and

receptacle moving means for pouring burden from the receptacle into the furnace.

10. Apparatus according to claim 9 having a hopper about the furnace opening to funnel flowing burden through the opening.

11. Apparatus according to claim 10 in which the closure means is connected to furnace superstructure to be moved completely out of the furnace opening and leave it unobstructed.

12. Apparatus according to claim 10 having a downwardly depending skirt suspended from the furnace top, said skirt bottom being wider than the receptacle mouth and of substantially less width than the furnace adjacent thereto.

13. Apparatus according to claim 12 in which the skirt is steel protected by insulating material.

14. Apparatus according to claim 12 in which the skirt is comprised of a grid-like structure which retains burden from flowing t-herethrough but permits flow of gas through openings in the grid.

15. Apparatus according to claim 12 in which the skirt has an upper portion of impervious steel and insulating material and a lower portion of grid-like structure which retains burden from flowing therethrough but permits flow of gas through openings in the grid.

16. Apparatus according to claim 9 in which the sealing means is extensible by fluid pressure into sealing engagement between the receptacle outer surface and furnace inner surface.

17. Apparatus according to claim 9 in which the furnace opening and receptacle mouth are substantially aligned and horizontally positioned, and the receptacle is mounted to rotate about a horizontal axis to empty burden therefrom by gravity flow.

18. The method of charging burden to a blast furnace operating at a high top pressure which comprises:

aligning the mouth of a burden-receiving hollow receptacle located inside the top of a blast furnace with a closed opening in the furnace top to receive burden therethrough;

temporarily sealing the outer surface of the receptacle to the inside of the furnace against gas flow therebetween by means of a seal circumscribing the furnace opening and receptacle mouth;

opening the furnace opening and conveying burden from outside the furnace, through the furnace opening and receptacle mouth into the receptacle;

closing the furnace opening against gas flow and releasing the seal between the receptacle and the furnace;

moving the receptacle to discharge the burden therefrom into the furnace body;

returning the receptacle into position with its mouth aligned with the closed furnace opening; and

repeating the said operations to operate the furnace at a high top pressure.

19. The method of claim 18 in which the gas pressure below the closed furnace opening is reduced to close to atmospheric pressure before the furnace opening is opened.

20. The method of claim 18 in which the gas pressure in the receptacle is increased to about the furnace pressure before the seal between the receptacle and furnace is released.

21. The method of claim 18 in which the burden leaving the receptacle is delivered to a vertical burden retaining grid-like skirt positioned inwardly from the furnace walls and the burden flows radially out the bottom edge of the skirt.

References Cited UNITED STATES PATENTS ROBERT G. SHERIDAN, Primary Examiner. 

1. APPARATUS FOR DELIVERING MATERIAL TO A VESSEL HAVING AN INTERNAL GAS PRESSURE DIFFERENT THATN THE EXTERNAL GAS PRESSURE APPLIED TO THE VESSEL COMPRISING: A VESSEL HAVING AN OPENING THROUGH WHICH MATERIAL CAN BE DELIVERED OR SUPPLIED FROM OUTSIDE TO INSIDE THE VESSEL; CLOSURE MEANS WHICH MOVABLY PLUGS AND LOSES THE VESSEL OPENING TO KEEP THE VESEL INTERNAL GAS PRESSURE DIFFERENT THAN THE EXTERNAL PRESSURE; A MATERIAL-RECEIVING OPEN-MOUTHED HOLLOW RECEPTACLE MOVABLY MOUNTED IN THE VESSEL SO THAT THE MOUTH CAN BE BROUGHT INTO COMMUNICATION WITH THE VESSEL OPENING; SEALING MEANS FOR BLOCKING PASSAGE OF GAS BETWEEN THE VESSEL INTERIOR AND EXTERIOR AT LEAST WHEN THE VESSEL OPENING IS OPEN, SAID SEALING MEANS CIRCUMSCRIBING THE VESSEL OPENING AND RECEPTACLE MOUTH AND BEING CAPABLE OF SPANNING THE DISTANCE BETWEEN BETWEEN THE RECEPTACLE OUTER SURFACE AND VESSEL INNER SURFACE; AND RECEPTACLE MOVING MEANS TO DISPLACE THE RECEPTACLE AND POUR MATERIAL FROM THE RECEPTACLE THROUGH THE MOUTH AND INTO THE VESSEL. 